Devices for sealing the edge of a sheet of plastics film or the like are shown in U.S. Pat. No. 3,505,725 issued Apr. 14, 1970; in U.S. Pat. No. 3,893,212 issued Jul. 8, 1975 and in U.S. Pat. No. 3,999,258 issued Dec. 28, 1976 all by Walter Curry one of the inventors herein.
In each of these devices there is shown a channel member which has a longitudinal channel extending along a length of the channel member and a locking strip which can be inserted into the channel and engaged under side edges of the channel so that the locking strip is held in place. The locking strip is slightly loose within the channel so that one or more sheets of plastic film can be engaged into the channel and underneath the locking strip so as to be held in place between the locking strip and the channel.
This arrangement is used in many different circumstances. In one particular end use, the arrangement is used to seal together two overlying sheets of the plastic material so as to form a seam therebetween. This is particularly useful for closing the ends of large bags for example the very tubular bags used for storing silage in the field. However very many other uses are available for an arrangement where two overlying sheets of plastic film are fastened together?
One difficulty in using the locking system disclosed in the above patents is that of inserting the locking strip into the channel member, particularly when the channel member and the locking strip are relatively large and therefore relatively stiff in order to engage and seal the relatively thick plastics material necessary for large bags.
U.S. Pat. No. 3,893,212 shows two different arrangements of tool which can be used to insert the locking strip into the channel. In one arrangement the channel is generally symmetrical on each side so that the locking strip is bent inwardly at its edges to tuck into the channel. In an alternative arrangement the channel is stiffer and more containing on one side allowing the locking strip to be inserted into that side following which the other side of the locking strip is tucked under a softer more pliable edge piece of the channel member.
Typically when using even the larger arrangements of this type, a rolling tool or wheel somewhat similar to that shown in FIGS. 3 and 4 of the above U.S. patent is used to engage the edge of the locking strip to push it into place. This is a hand operated tool which slides along or rolls along the locking strip. In a situation where it is necessary to close a large bag, it is necessary for the user to crawl along the edge of the bag pushing the tool along the locking strip while holding the locking strip in the required position. This is sufficiently difficult that it has led to some resistance to use of a system of this type thus reducing potential sales and thus reducing the possibility for the user to utilize the effective sealing action of a device of this type.
In some cases therefore, in the field, the ends of such large bags are closed by simple crude mechanisms using wooden strips and the like which are rolled at the edge of the bag. This crude system is sometimes used in replacement for the effective sealing action of the device of the above type in view of the difficulty of the installation.
It is one object of the present invention, therefore to provide a tool which can be used to more effectively insert the locking strip into the channel member in an arrangement of this type.